Back in the day

The accident at the Chernobyl nuclear power plant is regarded as the worst nuclear accident in history. Radioactive debris from the disaster drifted across parts of the western Soviet Union, Eastern Europe, Western Europe, Northern Europe, and the eastern US. Large areas of Ukraine, Belarus, and Russia were badly contaminated, resulting in the resettlement of hundreds of thousands of people and a disputed number of deaths. What caused the accident?

Feature

A lucid dream is a dream in which a slumberer is aware that he or she is dreaming while the dream is in progress. During lucid dreams, it is often possible to exert conscious control over characters and environments, as well as to perform otherwise physically impossible feats. Children tend to enter such dream states more easily than adults, but there are techniques one can learn to intentionally induce a lucid dream. What is the wake-back-to-bed method and how does it encourage lucid dreaming?

Born on a day like today

Richter was an American seismologist most famous for creating the Richter magnitude scale, which quantifies the size of earthquakes by assigning each quake a single number based on the measurement of seismic waves. The scale is logarithmic, so the amplitude of the waves increases by powers of 10 in relation to the Richter magnitude numbers. Numbers for the Richter scale range from 0 to 9, though no real upper limit exists. Who collaborated with Richter in developing the measurement system?